The present invention relates to cycle defrost refrigerator wherein defrost of the fresh food compartment evaporator is accomplished during the compressor OFF cycle primarily by convection of the relatively warm above freezing fresh food compartment air and through the heat leakage entering the fresh food compartment and more particularly to a control system for a cycle defrost refrigerator incorporating a roll-bond evaporator.
Generally in a cycle defrost refrigerator the temperature of the fresh food compartment is maintained by sensing the true temperature of the evaporator. This requires that the entire length of the thermostat control capillary tube be maintained in heat exchange relationship with the evaporator. Traditionally many cycle defrost refrigerators suffer from the inability of the control capillary to sense the true fresh food evaporator conditions under critical usage conditions. This often results from the inconsistencies of arranging the control capillary tube relative to the fresh food evaporator so that it will sense accurate evaporator conditions. These control errors often result in residual icing problems, premature compressor trip-offs, and a wide dispersal of operating response characteristics. One common manner of securing the control capillary to the evaporator to insure that the full length of the capillary tube is in contact with the evaporator has been to employ a plurality of clamps spaced along the entire length of the capillary tube. This method requires the use of external parts and labor to secure them to the evaporator and falls short of solving the problem since the relatively small diameter capillary tube realistically cannot conform to the surface of the evaporator.